The invention relates to a lifting apparatus which permits vertical movement of the load to be picked up and which is especially suitable for forklifts of various model sizes.
According to Patent DD-WP No. 134,633 there is known a lifting apparatus, especially suitable for forklifts, whose kinematic main system consists of a four-membered chain drive which is driven by a lifting cylinder, and which includes a frame of a power-propelled vehicle, a control lever, a supporting arm and a rocker. The system which stabilizes the fork support comprises tie rods or pressure bars arranged in parallel and pivotally connected to each other. On the frame of the power-propelled vehicle, eccentrically, on one end in a joint in front of the front-axle, the control lever is pivotally suported; at its other end, in a joint the supporting arm is pivotally supported; at the rear section of the supporting arm in a joint, the rocker is pivotally supported; between these two joints, the piston rod of the lifting cylinder is pivotally supported; and at the front section of the supporting arm in a joint, the fork support pivotally supported.
A system for positionally stabilizing the fork support is arranged eccentrically on one side and consists of tie rods arranged parallel to the supporting arm and to the rocker, the tie rods being operatively connected to each other via a bearing plate.
Furthermore, according to Patent DD-WP No. 156,359, there is known a lifting apparatus whereby a control lever, which is supported in a support detachably mounted on the vehicle frame, is connected to one end of a connecting bar. The connecting bar is supported at its other end on a compensating car which can be conveyed horizontally in the driving direction on the vehicle frame. In the compensating car there are also supported the rocker and an inclination cylinder which is functionally connected with the tie rod via an adjusting lever and the rocker. Because of the great space requirement, the individual displacement points and joints of the lifting apparatus cannot be realized very well and require a high material use.
According to Patent DDR-WP No. 225 854 A3, there has also been proposed a lifting apparatus whereby a support arm provided at one end with a fork support is supported on a support assembly provided on the vehicle frame. The support arm is provided with a joint for the piston rod of the lifting cylinder which, with its lifting cylinder displacement being provided at the lower end, is arranged in a pocket of a side part of the vehicle frame. The other end of the supporting arm is provided with a rocker head with joints for the tie rods and the rocker whereby the rocker connected thereto is operatively connected via the compensating car to a guide rail which is detachably fastened on the side part. The side part with the pocket for the displacement of the lifting cylinder is connected in the front area via a bending-resistant and torsion-resistant upper transversal rod and a detachable tie rod, and in the rear area via a box section and a counterweight having an asymmetrical mass distribution which is resistant to bending and torsion and is connected to the opposite side part.
At the front ends of the two side portions of the vehicle frame, there is a support assembly consisting of two displacement blocks, which are symmetricaly arranged in relation to the longitudinal axis of the vehicle, with face plates which are pivotally connected to the displacement blocks and which can be clapped upwards, and which are operatively connected to the fork support.